Turbine apparatus



April 4, 1961 W. E. KEENEY ETAL TURBINE APPARATUS Filed Feb. 2, 1959 IIIII INV'E NTORS WILLIAM E'.KEENEY WILLIAM R.BERRY ALVI L. sTocK BY 9 1tends transversely ofthe rotor-axis and they 'arediyided TURBINE ArrWilliam E. Keeney, Haverto'wn, Pa, William R. Berry, Camden, N.J., andAlvin L. Stock, Prospect Park, Pa, assignors to Westinghouse ElectricCorporation, East Pittsburgh, Pin, a corporation of Pennsylvania FiledFeb. 2, 195a, Ser. No. 790,496

Claims. c1. 253-39 This invention relates to elastic fluid turbineapparatus, especially steam turbines, and more particularly to animproved construction of the casing, the valve chest,

and the passagewaysbetweenthe valve chest and the provided withgovernor-controlled valves that are sequentially movable to open andclose a plurality of flow paths between the chest and the passageways.During partload operation, for example, some valves will be open,otherswill be closed, and steam will flow'through those passageways opento the valve chest.

Where apparatus of the type setforth experiences fre:

qt ient load changes or frequent starting and stopping, and the inletsteam temperature is at least 850 F., fatigue failures, in the casingflanges and the nozzleboxes may be caused whentheir component partsaresubject'ecl to repeated, alternately large and small temperaturejdiiierentials. This condition is termed thermal cycling? and is thoughtto" be the major cause of fatigue failures in Casing and nozzle'boxparts. I a

The construction disclosed in U.S,' Patent 2,527,445, issued October 24,1950, toGeorge-W'. Pentheny and pableof coping with the problemofthermal cycling, even 1 for inletsteam temperatures above. 12 0 0" F.For commercialreasons,however, itisfdesirable to provide an arrangementas efiective as .Pen'thenys butiless expensive t to construct. Moreparticularly, the problemhasiarisen in turbines of single-wall casingconstruction and driven by steamj'having an inlet temperature inrthe'rangeof be- According" .to the present inventiom'thelcasing is of vtubular, single-wall construction withan opening formed therein.Anfinteg'rally castacavernous body is provided for conducting theelastic fiuid to nozzle 'grou'pswithin thecasing; The cavernous body,which may be of higher. strength material than the casing,'compfisesavalve chest andwall structure including partitionsdefiningfpassageways or'noz'zle boxes between the chest and the nozzlegroups} The valve chest is formed integrally with the wall structure, asis a "circumferentially and, axially exthe casing, and

tending :fiange which his the'opening in is joined to the margin thereofby welding.

, 2,978,223 Patented Apr. 4, 1961 Another condition which imposesbending stresses on assigned to the assignee of the present invention,isca- I The passageways are arranged in a series which ex- V into atleast-two groupsiwhich are spaced from each other, as well as from thewall ofthepcasing. Thisaarfrangement permits portio'nsot thewallstructure connect ing, the partitions teas grojup great-exp ns inwithout, imposing force ire'ction a .ings ii) as therearenozzle' groups3i), Inthis ernbodi ment, there in .SlX.Q1 JH ll'l gS f'@ and six nozzlegroups.- i ed n a horizontal ag;-

results when one partition undergoes greater thermal expansion than aneighboring partition in the same group.

the cure for this condition it is necessary to mention that it is causedduring part-load operation wherein a partition common to an open and aclosed passageway is heated by the steam flowing through the openpassageway, and the other partition of the closed passageway isunheated. In accordance with the invention, each group of passagewayshas conduit means providing restricted steam communication between itspassageways so that the temperature difference between its partitionswill be minirnized. When, in operation, at least one passageway of agroup has fluid passing therethrough and there is at least onepassageway of the same group closed to the valve chest, a small quantityof fluid bleeds from the open passageway into the closed passageway inorder to hea t its surrounding wall structure. The detrimental effectsof'a large temperature difference between the partitions are therebyavoided.

The various objects, features and advantages of the invention willappear more fully from the detailed de 'scription which follows, takenin connection with the ac- Fig. 2 is a transverse sectional view takenon line H -II of Fig. 1;

Fig. 3 is an exploded, perspective view of the appar a tussof Fig. l,but with the nozzle groups removed; and, 1 Fig. 4 is a horizontalsectional view taken along line IVIV of Fig. 2.

Referring to the drawing in detail, thelinvention'is.

applied to an axial-flow steam turbine comprising a'cylinder or casingit which is formed about a horizontal axis and includes anjupper half 12and a lowerhalf 14, these halves having'respectivefianges 16and18; The

casing halves are joined together at the flanges by suitableboltsandhavea rotor 20 journalled therein and c0- "axially alignedtherewith, A plurality of stages for extracting energy frornthesteamjisconventicmally provided 1 lay-cooperating, annular rows of blades,'generallyindiesteem 22. In orderto minimizetheleakage of steam I fromtheinlet end; of the casing 10, the usual annular seals 26 are providedbetweenthe'rotor and casing parts v Pressurized steam is conductedthrough an opening inthe upper casing half 12 to groups oino'zzles an,ar-

ranged in an annular array upstream of'the first stage blading byI1l6&11S. Of: Zi. cavernous body 28, the latter.

beinglof integraleonStruction andincludingz, ayalve chest 32,walistructure'fi and acircumierentiallyand axially extending, arcuateflange memberiie. :The flange member 36 is adapted to iit a similarshapedopening .37 in theupper casing half 12 and their respective manginal portions are joinedtogether by welding. The loation of the weldedjointwill be discussed. hereinafter in greater detail.

.: Ihe'valv'e GhSP t 3 2' has inletopenings33, "adapted for.

connection to "3T.-SO11'Y:C6 of. pressurized steam such as a boiler(notgshown), .and also has "as many outlet open- These openings 4% areair .t'l' extendsj'tr-ansverselyespec to the? rotor axis Preliminary todescribing a I, The valve -chestlsz.is fnrtherfprovide'd*with ka'l Ivalve "42 for eachoutlet'ope'ning}itbthese valvesbeing carried by avertically movable, horizontal lift bar 44. Movement of the lift bar 44moves the valves 42 in succession to open and close the openings 40, allof which is well knownin the art. s

The primary function of the wall structure 34.is to conduct the elasticfiuidfrom the outlet openings 40 in the valve chest 32 to the nozzlegroups 30. Since some of the valves 42 may be in position to close someopenings 40, while other openings are opened to the valve chest 32, itis desirable for the wall structure 34 to define a plurality ofpassageways 48 downstream of the chest between associated openings andnozzle groups. To this end, there is a series of horizontally spaced,internal partitions 46 included in the wall structure 34, which seriesextends transversely of the rotor axis and defines fluid passageways 48.The lower casing half 14 is provided with two passageway extensions 49for the purpose of completing the means for conducting steam from thevalve chest 32 to the two nozzle groups 30 in the lower casing half 14.A centrally disposed pair of partitions 46 also define a space 50 whichdivides the passageways 48 into two groups 52 and 54. The end partitions46 of the series are arranged in spaced relationship with the interiorwalls of the upper casing half 12. so that, as viewed in Fig. 2, thereare left and right spaces 56 and 58, respectively, between the wallstrucwhich members 59 extend transversely of the rotor axis and connecttogether the partitions 46 of each group. (See Fig. 4.) Unlike prior artstructures, the members 59 can elongate due to thermal expansion withoutbuckling or damaging the casing because the spaces 50, 56 and S8 permitthe unresisted elongation of the members 59 of either or both groups.The elimination of repeated stressing of the rigid casing 10 and thewall structure 34 prevents their failure and avoids difiicult and costlyrepairs. Additionally, the wall structure 34 may be made from astronger, through more expensive, material, since the wall structure ismade separately from the upper casing half 12. Furthermore, the spaces56 and 58 are provided without having to use a coring process duringcasting of the body 28, as is required for making the space 50.

As mentioned previously, the cavernous body 28 includes a flange member36 formed integrally with the wall structure 34 and welded to portionsof the upper casing half bounding the opening 37 therein. It isnoteworthy that the flange member. 36 is of arcuate'shape and extendsaxially and circumferentially about the retor axis, as do thesurrounding wall portions to which it is welded. The line of jointurebetween welded parts is axially and circumferentially aligned with thewall portions bounding the opening 37 in order to preserve the axialintegrity of the upper casing half 12. As can be seen in Fig. 2, whereinthe flange member 36 is mostly shown in dotted arcuate lines, thepartitions 46 reinforce the wall structure 34 in axial direction, sinceportions of the partitions 46 are in axial alignment with the uppercasing half 12, the welded joint, and the flange member 36. This featurecan be best appreciated by now referring to Fig. 1 and visualizing steamforces within the casing 10' operating in axial, outwardly oppositedirections on the end walls thereof; these forces tend to separate theeasing into two halves along a circumferential line extending throughthe opening 37. By

" placing the welded joint and the partitions 46in axial alignment withsurrounding portions of the upper cas-I ing half 12 there is no momentarm provided, which would impose bendingforces on the joint; Thecavernous bedyQB. furtherincludes conduit means,

such as *an inte rnal nifold 6t},- providingrestricted which may be usedfor forming the manifold 60 it is most conveniently formed during thecasting of the cavernous body 28 by a coring process that is well knownin the foundry art. The purpose of the manifold 60 is to bleed a smallquantity of inlet steam from any passageway 48 open to the valve chest32 and deliver it to the closed or inactive passageways in the samegroup in order to heat their wall structure. Preheating of the wallstructure prevents it from suffering a thermal shock, that is, a largetemperature gradient in a short period of time, as a result of thesudden opening of the closed passageway and introducing high temperaturesteam thereto. Preheating also minimizes the temperature differencebetween the partitions 46 of a closed passageway in the situation whereone of its partitions is in common with an open passageway through whichhot steam is flowing. Thus, the partitions 4-6 of a closed passagewayundergo a similar amount of thermal expansion and the portions of thewall members 59 connecting them do not warp.

Referring again to Fig. 2, it will be noted that the valves 42associated with the right-hand group of passageways 48 are arranged toopen in succession from left to right, and it follows that elastic fluidwill flow through the left-hand passageway before the other two in thatgroup. During part-load operation, forexample, the common partition 46between an open and closed passageway, would be much hotter than theother partition of the closed passageway were it not for the smallquantity of steam issuing from the manifold 60 into the closedpassageway. During frequent load changes of a turbine not having suchmeans for heating the closed passageways, a condition known as thermalcycling may be caused, wherein one passageway will be continually opento the valve chest 32, and an adjacent passageway will be alternatelyopened and closed to the valve chest, thus subjecting the portions ofthe wall members 59 connecting the partitions of the alternately openedand closed passageway to alternating bending moments. Withoutpreheating, thermal cycling can cause a fatigue failure in this portionof the wall member '59. The manifold 60 provides a solution to thisproblem.

From the foregoing, it will be apparent that the spacing of thepassageways 48 from the upper casing half 12 prevents buckling of themembers 59 and the transfer of forces to the casing when the members 59elongate due to, thermal expansion; the preheating of the passage ways48, by means of the manifold 60,reduces the temperat'ure differencebetween adjacent partitions 46 and minimizes the chances of the wallmembers 59 failing from fatigue; and the structural arrangement lendsitself well to inexpensive fabrication, while not impairing the strengthof the casing 10 for resisting axial forces tending to separate thecasing in two halves along a circumferential line through the opening37. 7

While the invention has been shown in but one form, it will be obviousto those skilled in the art that it is not so limited, but issusceptible of various changes and modifications without-departing fromthe spirit thereof.

What is claimed is:

1. In an elastic-fluid turbine, a casing, a rotor, blading carried bythe rotor and the casing, said casing including a wall portion formedabout the rotor axis and being exteriorly of the casing, said conductingmeans compris ing a plurality of nozzle groups, a valve'chest, and Wallc ludingan exterior surface portion which fits said open; ingand isjoined to the margin of said wall portion communication between thepassageways48 of each of.

i two groups 52 and- S l Qfthe various methods structure integrallyformed with said valve chest and defining a series; of fluid passagewaysbetween the chest and each of the nozzle groups, said wall'structure.in-

bounding said opening-said wall structure including; a;

series of partitions which are spaced from each other and the casing,said series extending transversely with respect to said rotor axis,there being two spaced partitions disposed between at least one pair ofneighboring passageways.

2. In an axial-flow elastic-fluid turbine, a casing, a rotor having arow of blades, said casing including a wall portion formed about therotor axis and being provided with an opening in said wall portion, anannular array of nozzle groups positioned upstream of said blades, acavernous body extending through said opening for conducting elasticfluid to the nozzle groups from a source of pressurized fluid exteriorlyof the casing, said body being integrally formed and comprising a valvechest, wall structure connected to said valve chest and defining aseries of fluid passageways downstream of the chest, and an axially andcircumferentially extending flange member connected to said wallstructure and fitting said opening, said wall structure including aseries of partitions which are spaced from each other and the casing,said series extending transversely with respect to said rotor axis,there being two spaced partitions disposed between at least one pair ofneighboring passageways, the margin of said flange member and the marginof said wall portion bounding the opening being connected together alonga line of jointure that is axially and circumferentially aligned withsaid wall portion, said flange member, and portions of said partitions.

3. In an axial-flow elastic-fluid turbine, a casing, a rotor, saidcasing including a tubular wall portion formed about the rotor axis andbeing provided with an arcuate opening in said wall portion, meansincluding an annular array of nozzle groups and a cavernous bodyextending through said opening for conducting elastic fluid from theexterior to the interior of the casing, said body including a valvechest, wall structure integrally formed with said valve chest anddefining a series of fluid passageways extending from the chest to therespective nozzle groups, and means connecting said wall structure tosaid tubular portion adjacent said opening, said wall structureincluding a series of horizontally spaced partitions which extendstransversely with respect to said' rotor axis, there being two spacedpartitions centrally disposed in said series between at least one pairof neighboring passageways, said two spaced partitions dividing theseries into two groups each comprising a plurality of passageways, andmeans providing restricted communication between the passageways of eachgroup.

4. In an axial-flow steam turbine, a horizontal-axis rotor, a casing,blading carried by the rotor and the casing, said casing having anopening formed therein, an annular array of arcuate nozzle groupspositioned upstream of the blading, a cavernous body extending throughsaid opening for conducting steam to the nozzle groups, a weldedconnection between the body and a portion of said casing bounding theopening therein; said body comprising a valve chest having an inletopening and as many outlet openings as there are nozzle groups, wallstructure including horizontally spaced partitions integrally formedwith'said valve chest and defining steam passageways downstream of therespective outlet openings, valves for the respective outlet openingsmovable in succession to open and close said outlet openings, therebeing two partitions defining a space between at least two groups ofneighboring passageways, and conduit means formed in said body providingrestricted steam communication between the passageways of each group. a

5. In an axial-flow steam turbine, a horizontal-axis rotor, a casingincluding an upper half and a lower half, blading carried by the rotorand the casing, said upper casing half having an opening formed therein,an annular array of arcuate nozzle groups positioned upstream of theblading, a cavernous body extending through said opening for conductingsteam to the nozzle groups; said body comprising a valve chest having aninlet opening and as many outlet openings as there are nozzle groups,valves for the respective outlet openings movable in succession to openand close said outlet openings, wall structure including horizontallyspaced partitions integrally formed with said valve chest and definingsteam passageways, there being one passageway between respective ones ofsaid outlet openings and said nozzle groups, and an axially andcircumferentially extending flange member formed integrally with saidwall structure to fit the opening in said upper casing half and beingjoined to the margin of said upper casing half bounding the openingtherein, said partitions being spaced from said upper casing half, therebeing two partitions defining a space between two groups of neighboringpassageways, and conduit means formed in said body providing restrictedsteam communication between the passageways of each group.

References Cited in the file of this patent UNITED STATES PATENTS2,294,127 Pentheny Aug. 25, 1942 2,304,993 Franck Dec. 15, 19422,308,897 Stearns Ian. 19, 1943

